Thermodynamical Properties of Bicomponent Mixtures of Liquid Crystals Cholesteryl Pelargonate and Nonyloxybenzoic Acid

Transition temperatures, transition enthalpies and entropies of different mesophases of the binary mixture of cholesteryl pelargonate (ChP) and nonyloxybenzoic acid (NOBA) have been measured on a differential scanning calorimeter and optical textures of different mesophases have been confirmed on a polarizing microscope. Eutectic point has been observed at 28 ± 2 mole percent of NOBA from the variation of transition temperature, enthalpy and entropy of the crystal to mixed crystal phase and the mixed crystal phase to mesophase with concentration of NOBA. Stability of SmA phase increases on addition of NOBA. SmA* phase has been observed in between SmA and Ch phases for NOBA concentrations between 18 and 50 mole percent. A very wide cholesteric range of about 50 °C has been observed in cooling in the concentration range of 60 to 90 mole percent of NOBA.